In the photo you can see that the top trace moves in the opposite direction of the bottom, indicating the waveforms are inverted.
![white noise truerta white noise truerta](http://hyperphysics.phy-astr.gsu.edu/hbase/Audio/imgaud/equal.gif)
Two traces on the scope displayed the left and right channels separately. Running square waves and sawtooth waves reveals that the rising and falling edges are modulated by the effect to a point where higher frequencies will pass, but low frequencies are inverted. Running sine waves through the Tape Comp reveals that there is indeed a drastic phase inversion. The Thor Synthesizer was connected to a mixer with a Scream 4 inserted on the right channel only. In Reason, I created a basic configuration of a Thor being self-triggered with the internal sequencer with the analog oscillator and no filters.
![white noise truerta white noise truerta](http://www.scielo.org.co/img/revistas/teclo/v18n34/v18n34a09fig05.jpg)
In order to determine the linearity of the phase response of the Scream 4, I broke out the old oscilloscope and wired up a stereo jack to a pair of bnc connectors to monitor two channels coming from my workstation. As the photograph of the oscilloscope indicates, It’s not a perfect phase reverse because the signal is also being processed by the effect, but it’s enough to cause some problems if you’re not aware of this characteristic. I set the output evels by ear and frequently make running changes while the movies are playing (makes watching movies an interactive experience ).In case you didn’t know, the Scream 4 Tape Compression algorithm induces somewhat of a phase inversion to signals passing through the device. I've never bothered to 'calibrate' my system. I can't specifically address the multichannel question. Move 12" or so away from the measurement position and the room interactions (and corresponding measurements) will of course change. There is a fundamental issue with using any of these programs, and that is where the measurement is taken.
#White noise truerta free
Those people having LspCAD can play with the free 'JustMLS' program available to users. I suggest trying the demos to see which program is more appropriate to your needs/wants. The ETF demo doesn't allow saving of data. The TrueRTA demo is of course only 1/3rd octave. It's much easier to show this to some one than try to explain via the 'net'īTW, both offer a demo versions. If you want a quick and easy look at the speakers and their interaction with the room use TrueRTA. So if you want a more comprehensive loudspeaker measurement/evaluation system then use ETF. Other than that ergonomic complaint Jon thinks ETF is a good buy. The standard is divisions of '10', so 10Hz, 100Hz, 1000Hz, etc. To him that makes it weird to try and figure out the frequencies between those indicators. Jon doesn't like ETF because the plot divisions are in multiples of '2' and can't be changed. It doesn't work in 'real time' but neither do any MLS programs. If one want's the interactions then just use a longer duration window.ĮTF does more things such as MLS, waterfall plots, impluse response, etc. When I say 'not accurate' in the above paragraph I'm talking about having the room interactions eliminated. If the window duration is longer then the bass is more accurate but the mid/high frequencies aren't. If the window duration is short then the mid/ high frequencies are accurate, but the bass isn't. The reason for doing this is to eliminate the interaction between the speaker and the room.
![white noise truerta white noise truerta](https://demo.pdfslide.net/img/380x512/reader018/reader/2020010707/54e2bd374a7959ba1b8b458b/r-2.jpg)
![white noise truerta white noise truerta](https://audioxpress.com/assets/upload/images/AudioTestNoisefigure1.jpg)
And it's playback is captured in a 'window' of time, the duration of which is specified by the user. MLS (Maximium Length Sequence) is where a burst of what is basically 'shaped white noise' is send through the system. It's impossible to isolate the speaker from the room unless one is making the measurements VERY nearfield. 1/24th octave readings made in real time made with pink noise. TrueRTA is a very nice plug-n-play program that provides 1/3, 1/6. Jon's in England for the next 10 days and doesn't have 'net' access so I'll attempt to give you a reasonable answer.